A person may develop a hernia if the abdominal wall is weak and is not capable of keeping the peritoneum in place when larger pressures occur within the abdominal cavity. When a hernia occurs, the peritoneum bulges through a defect within the abdominal wall. Repairs of a hernia defect can be accomplished either anteriorly or posteriorly and may be corrected through the application of sutures, flat mesh prosthesis, prosthetic plugging devices or devices manufactured as multiple layer devices (such as the Prolene Hernia System, manufactured by Ethicon, Inc)
With the advent of minimally invasive surgery, there is a desire to repair the hernia defects through an incision, which is minimal. To this end, anterior approaches that provide posterior repairs have been suggested by Dr. Gilbert and others.
One technique involves making an incision near the site to be repaired, dissecting the tissue down to the peritoneum, dissecting the tissue between the fascia and peritoneum and applying a flat piece of mesh under the site of the defect. The separated tissue layers are held in a retracted position to provide room for the mesh application. The flat mesh is wound onto two instrument shafts (similar to a scroll) and is inserted through the incision. Once in place, the two instrument shafts are rolled in opposite directions to unroll and deposit the mesh at the site of the repair. This technique requires excellent dexterity in order to manipulate the instruments, both to capture the mesh and to unroll it properly.
A second anterior approach suggested by Dr. Gilbert is to make an incision at the site of the defect. The tissue is dissected to the defect. Once the defect is visualized, a sponge is inserted through the defect and the fascial layer is dissected away from the peritoneum. Once the dissection is complete, a two layer mesh prosthetic device (two layers attached at central position) is inserted through the defect and the upper layer is pulled back out of the defect. The surgeon then inserts a finger alongside the central portion of the device and attempts to deploy the lower layer of mesh outward away from the defect into a flattened position on top of the peritoneum. This method does not ensure even distribution of the lower layer since the deployment action is based on a single point of contact with the surgeon's finger.
Applicator devices intended to deploy mesh devices and prosthetic devices with integral opening mechanisms attached have been suggested to improve the ability to deploy the mesh or prosthetic device into a flat condition. U.S. Pat. No. 5,176,692 discloses a balloon applicator device that enables the inflation of a balloon with mesh attached at the site of the defect. The device requires the addition of a means to inflate the balloon once it is placed at the site of the defect to be repaired. This addition of an inflation mechanism extends both the time and cost of the procedure.
U.S. Pat. No. 5,258,000 discloses a means for unfolding the mesh in position through the attachment of an elastic/semi-rigid ring to a piece of flat mesh. The mesh is placed in position in a folded condition and is released. Ideally, the elastic element will exert an opening force to allow the mesh to return to a flattened condition. Unfortunately, the addition of stiffening elements to a flexible piece of mesh as a permanent implant results in patient discomfort and increases the patient awareness of the presence of the device.